Pump Retrofit Keeps Science Center Comfortable

St. John’s Univ., a Benedictine school in the town of Collegeville, MN, undertook a heating system retrofit of its Peter Engel Science Center just in time for the 2013-2014 winter.

Photos: Craig Lassig

Pump Retrofit Keeps Science Center Comfortable Minnesota campus upgrade boosts efficiency despite record-cold winter.

Minnesotans have a well-earned reputation for toughing out the snow and cold each winter, but even this hardy state was tested over the harsh 2013-2014 cold season.

With at or near record lows, heating systems across

Minnesota were put to the test. While many commercial buildings required more energy to keep occupants comfortable with consistently below-freezing temperatures, one private school in the south-central region actually saved money this winter.

St. John’s Univ., an all-male Benedictine school in the town of Collegeville, undertook a heating-system retrofit just in time. Campus HVAC service technician David Schlumpberger oversaw the project. “We were approached by our local wholesaler, Ferguson Enterprises, Roseville, MN, with the suggestion that we consider replacing the pumps in the Peter Engel Science Center with Grundfos Magna3 smart circulator pumps,” he said. “I wasn’t aware of them before, but the existing pumps were nearing the end of their lives, so we decided to do something more efficient.” The pumps are manufactured by Grundfos Pumps Corp., Downers Grove, IL.

Energy efficiency is important on every campus, but environmental stewardship is a core Benedictine tradition at St. John’s, which boasts an office of sustainability and sits on 2,700 acres that range from wetlands to lakes and prairies to forests. “The smart technology is a really good fit for a school that teaches students a respect for the land,” Schlumpberger explained.

Schlumpberger and his team opted for the circulators due, in large part, to the products’ sophisticated electronic technology and demonstrated energy efficiency. Al

Top, left. Grundfos sales representative Brian Soderholm worked on the St. John’s retrofit, which replaced four older pumps with smart circulator pumps. Each pump has a built-in energy meter and a flow-limiting function to save energy.

Below, left. Since the building wasn’t zoned and no variable-frequency drives were installed, the old system was operating full-bore throughout the heating season. The retrofit saw the new pumps running at 25% of the head of the old pumps, while still keeping the building warm.

Below. While many Minnesota buildings required more energy to keep occupants comfortable during consistently below-freezing temperatures, St. John’s Univ. actually saved money during the winter.

though the pump has a higher up-front cost than most conventional circulators, its performance produces fast payback on investment, post-installation.

A LOGICAL SOLUTION The unit is an energy-optimized, variable-speed, wet rotor circulator that features a permanent-magnet motor design that will cut power consumption as much as 85%. “These pumps adapt to existing situations and can be adjusted accordingly,” said Brian Soderholm, a Grundfos sales representative in Ramsey, MN, who worked on the St. John’s project.

“Grundfos offers a pump that has an integrated logic algorithm to ‘learn’ the varying energy-usage patterns of any application. This was a huge improvement over the Science Center’s antiquated pumps,” Soderholm added.

Replacing the four older pumps updated the system, increased efficiency, and improved building comfort. The pumps’ Autoadapt function saves energy and money by continuously fine-tuning power consumption, discharge head, and flow rates to meet the dynamic needs of the system.

Laid out in four wings, the Peter Engel Science Center is used primarily during the school year, running heat from fall through spring. It was built in the 1960s of concrete, typical of that era, and of the construction style found throughout the rural campus. “We had a feeling the old pumps were oversized, but there was no way to tell until we did the replacement,” Schlumpberger said.

The building contains two primary circulators, pumping hot water supplied by a steam-to-hot-water converter, with the steam coming from a central plant. There are four pumps on the secondary loops—each serving a different wing—feeding baseboard heating that uses pneumatic, three-way mixing valves to help regulate the temperatures.

Initially, Schlumpberger thought the old pumps

were on a variable-flow system. “But after the pumps were installed and we started it up, we realized that the system was not variable; it was a fixed flow,” he said.

BUILDING NOT ZONED Since the building wasn’t zoned and no variable-frequency drives were installed, the entire system was operating full-bore throughout the heating season. The team performed an audit of the existing pumps and found the north wing was originally designed for 41.5 gal./min. at 20 ft. of head; the south, 24.1 gal./min. at 21 ft.; the east, 23.7 gal./min. at 21 ft.; and the west, 17.4 gal./min. at 21 ft.

“As suspected, the engineers had oversized that older system,” said Soderholm. “Oversizing wastes energy and is hard on the pipes. In fact, we saw evidence of that in some copper piping that Dave’s staff removed. The insides of the piping were lined with ridges, indicating damage from excess velocity.”

The intelligent technology of the four new pumps

minimizes energy costs. The pumps have a built-in energy meter and a flow-limiting function. Even at reduced loads, the circulators save energy, compared with conventional circulators.

They’re also an all-in-one option for building owners, eliminating the need for costly installation of a companion flow meter, pressure and temperature gauges, throttling valve, constant-speed pump, or BTU meter.

With this circulator, it is easier to right-size the duty point. Getting the flow rate correct is important, obviously, because with too little you don’t get the heat you need. But if it’s too high, you waste energy.

“We were able to get the necessary flow rates at much fewer feet of head [lower pressure],” Soderholm said. “Over time, I think they’ll be able to slash their energy use even further. Even though this was not a system with variable-flow characteristics, the payback numbers are still really impressive.”

ENCOURAGING PAYBACK RESULTS When looking at the premium of going with the four Magna3 units versus another brand in its class, the payback for the Science Center will be less than 3 yr. for three of the new circulators and just slightly longer for the fourth. “We sized the pumps to match the old pumps, not knowing what their true system requirements were,” Soderholm said, explaining they had only the rating plates to go by, since their analysis was conducted during summer.

“Even though the pumps are larger than necessary for this building,” he continued, “it’s not wasteful, because we were able to dial them down with impressive results,” Now the north wing is at 39.6 gal./min. at 14.8 ft.; the south, 25.5 gal./min. at 9.2 ft.; the east, 21.1 gal./min. at 8.53 ft.; and the west, 12.8 gal./ min. at 7.2 ft.

What that translates into is an estimated annual savings of $693. “The bottom line is that the Magna3 is sophisticated and capable of doing everything the old pumps did, only better because it’s smart,” said Schlumpberger. “It can tell itself to slow down or speed up, based on current demand. Another benefit is that now we can get data off the pumps’ readout and learn more about the building’s needs.”

Schlumpberger added, “We just had the coldest winter in 30 years and we were running pumps at 25% of the head that the old pumps had, while keeping the building warm. In other words, we’re actually able to run the system at the original designed flow rate, using less power, less energy, and at less cost.”

With measurable retrofit results and evidence of other older heating systems on campus needing replacement, Schlumpberger is considering additional Magna3 installations.

“The Science Center project is a good barometer of the payback potential,” he said. “We will decide on a case-by-case basis, but it’s a very likely a possibility down the line.”

CBP

DATA CACHE

Want more information? The resources below are linked in our digital magazine at cbpmagazine.com/digital/oct2014.

Circle 8 on the Reader Service Card.

Watch a video on the Magna3 features and benefi ts.

View an installation video for the Magna3.

Download a Magna3 data booklet.

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